(a) Field of the Invention
The present invention relates to a multiple mode terminal supporting handoff between heterogeneous networks, and a handoff method thereof. More specifically, the present invention relates to a multiple mode terminal and a handoff method for interworking between various heterogeneous networks so as to provide a seamless data communication service without being affected by changes of wireless access environment in various communication networks, based on mobile Internet protocol (IP).
(b) Description of the Related Art
Recently, bidirectional wireless communication using portable communication terminals such as a notebook and a personal digital assistant (PDA) has been widely used as users' requests for the mobile Internet have increased.
Accordingly, a data communication method using a mobile communication network of a code division multiple access (CDMA) method based on a third generation network has been developed as a new wireless network. However, there is a limit to using data communication through the mobile communication network since the data rate thereof is lower than a high speed wired Internet network, and the cost thereof is high.
In addition, a conventional wireless local area network (WLAN) method in IEEE 802.11 may be applied to various areas including an area required for terminal mobility, an area in which it is difficult to arrange cables, and a network connection between a building and another building. The WLAN method is limited in that wireless data communication is performed around a fixed access point AP within a short distance, rather than providing mobility of a mobile subscriber station. Accordingly, a wireless broadband (WiBro) Internet system has been developed by combining the merits of high speed and high quality data communication services of the WLAN and a wide service range of the mobile communication network.
By using the 2.3 GHz frequency band, the WiBro Internet system in IEEE 802.16 guarantees mobility at 60 km/h within 1 km, and speeds of 3 Mbps download and 1 Mbps upload for each user.
The service area of the WiBro Internet system is narrow even though it has the merits of mobility and high speed data communication, and a high speed service is not provided for a mobile communication system based on CDMA due to the limited wireless capacity thereof. Therefore, when services and terminals for performing interworking between respective networks are developed, a seamless data communication service may be provided within a broad area since it provides users with the merits of a mobile communication network and a WiBro Internet network.
However, a high speed seamless data communication service may not be provided for users at a low cost since mobile communication terminals and WiBro Internet terminals have been independently developed in respective models. Therefore, when a mobile communication service user enters a WiBro Internet network service area, the service is required to be switched to the high speed WiBro Internet service, and when the user leaves the WiBro Internet network service area, the service is required to be switched back to the mobile communication service. In addition, it is required to develop a multiple mode terminal for concurrently supporting the data communication of the mobile communication network and the WiBro Internet network.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.